Fuel-oil burner



March 25, 1930. HACKFORD 1,752,173

FUEL OIL BURNER Filed Oct. 29, 1927 2 Sheets-Sheet 1 March 25, 1930. HACKFQRD I 1,752,173

FUEL OIL BURNER Filed Oct. 29, 1927 2 Sheets-Sheet 2 I gw K i I 5 5 l7 'z/wgwrom Patented Mar. 25, 1930 UNITED STATES- PATENT OFFICE JOHN EDWARD HACKFORD, OF LONDON, ENGLAND FUEL-OIL BURNER Application filed October 29, 1927, Serial No. 229,742, and in Great Britain November 4, 1926.

This invention relates to the wickless burning of oil fuel, such as petroleum and its products, without atomization or preliminary vaporization, by combustion of the oil on the surface of a body or film thereof.

case, when the burner has attained its working temperature, the heat derived by conduction or radiation from the flame converts the oil into vapour, either by evaporation or by evaporation combined with partial decomosition, and the vapour is afterwards urned with air. The point at which burning of the vapour occurs in burners of the evaporization type may be near to or com paratively remote from that at which vaporization is effected, but vaporization is here a definite operative step and is to be distinguished from the surface evaporation which occurs when a body of oil burns freely in the open air in a shallow vessel. Both atomizing and vaporizing methods suffer from well-known disadvantages which it is the object of the present invention to obviate.

If a pool or film of oil is caused to burn freely at its surface in an open containere. g. 1n a shallow pan in the open aira very smoky flame, unsuitable for practical heating purposes is obtained. I have discovered, however, that if the special conditions hereinafter set forth are adhered to a smokeless flame can be obtained from oil burning on the surface, without atomization or preliminary vaporization, and that this method can be successfully employed in burners of very simple constructions, adapted for a wide range of uses.

My experiments have shown that smokeless or practlcally smokeless combustion can be achieved if a body or film of oil of any desired length and of suitable limited widthfor example 2 to 3 inches across-while burning on the surface, is subjected to the action of a steady current of air, sufficient in quantity and velocity, which impinges upon and sweeps transversely across the burning surface without deflection and without encountering opposing currents. The limiting factors as regards width of burning surface and velocity of air current are that the width must not exceed that at which the flame can be adequately aerated by the current used, and the velocity must not be so great as to atomize the oil or blow it out of its container. A moderate air current, such as is obtainable with the draught of a domesticchimney, sufficies for many purposes. The method can be effectively put into practice in a burner consisting essentially of a shallow horizontally arranged trough of curved cross-section in whichfthe body or film or oil is maintained, and a deflector or guide extending down into the trough to near the surface of the oil, the arrangement being such as to cause an air current to impinge upon and sweep transversely across the surface of the oil at all points along the trough. The trough and eflector may be straig t, curved, or annular, according to the shape of burner required.

The invention consists in a method of burning oil fuel in which combustion is maintained ,at the surface of an elongated bod or film of non-atomized and non-vaporize oil of suitable limited width by means of a steady blanket of air which is caused to sweep transversely across the whole burning surface without deflection by encountering opposing currents or forces tending to restrict the flow whereby the products of combustion are continuousl removed by said blanket of air from such urning surface as they are formed.

By the term blanket of air is meant a continuous body of air as distinct from a number of separate streams or jets thereof, the current being such as adequately to aerate the flame Without blowing the oil out of its container. It is not essential for the velocity of the air to be the same at all points, rovided that the flow across the surface 0 the oil is steady at each oint.

Conveniently the blanket of air may be maintained by natural draught, such as that of a chimney, but any other suitable means may be employed.

In burning oil fuel accordin to he present invention it is essential that t e pressure in the region of the surface of the body or film of oil shall not appreciably exceed that of the atmosphere. Failure to comply with this condition results in the rapid heating up of p designed for use in connection with household and other stoves and heaters and for firing steam generators and other suitable boilers and furnaces Fig. 2 is a transverse vertical section and Fig. 3 a longitudinal vertical section through a muflle furnace of conventional type fitted with a modified form of the burner illustrated in Fig. 1.

The burner illustrated in Fig. 1 comprises a receptacle 1 in the form of a continuous and shallow annular trough, of semi-circular cross section, and having a base portion 2, an inner wall 3 and an outer wall 4, the inside edge of the wall 3 being preferably lower than the outside edge of the wall 4. The receptacle 1 is provided with a central air aperture 5. The said receptacle is adapted to retain a body or film of oil in a non-vapourized and non-atomized condition, which body or film of oil is, for the sake of explanation, indicated at 6. This body or film of oil is maintained by means of a suitable source of supply, the oil being fed into the receptacle by way of a pipe 8. The outlet end 8", of this pipe is bent over the rear edge of the receptacle so as to discharge the oil at a point which is within the entering stream of air whereb such outlet'end of the pipe is maintained y this air at a temperature below the boiling point of the oil. The oil is thus permitted to reach the interior of the receptacle in a non-vaporized condition.

The air for supporting combustion at the surface of the oil is caused to enter the receptacle through the central opening 5 over the wall 3 by means of a deflector 14, the lower edge 14 of which is just above and in close proximity to the surface of the body or film 6 of oil. By this means a steady blanket of air is caused to sweep transversely across the whole burning surface of the oil without deflection and without encountering opposing a1r currents.

The deflector 14 is shaped somewhat like a saucer and is supported in invertedposition upon and above the rim of the circular inner wall 3 of the receptacle by, for example, three legs, two of which are indicated at 15. The air entering through the aperture 5 passes between the inside surface of the wall 3 and the under surface of the deflector 14 and is thus caused to impinge upon and sweep trans versely across the surface of the oil 6 at all points along the trough, the products of combustion passing upwards into the enclosed space 16 forming the furnace of the boiler, heater or other apparatus to which the burner is fitted.

It will be understood that the dimensions and adjustment of the deflector for obtaining the best results depend to some extent upon the dimensions of the receptacle, draught and other conditions; but with the arrangement shown in Fig. 1 a deflector having the dimensions and position there indicated has in most cases been found suitable. The deflector may be supported adjustably, if that be desired, the legs 15 being replaced by" adjustablesupports, such, for example, as shown in Figs. 2 and 3. The adjustment should be such that, owing to the velocity of the air current, combustion occurs on the surface of the oil beyond the rim 14 of the deflector, littleor no combustion occurring within or below the deflector itself.

The form of burner illustrated in Figs. 2 and 3 and shown applied to a conventional mulfle furnace differs in three respects from the burner just described in connection with Fig. 1 viz (a) supporting the deflector from beneath by means of vertical rod-like supports 16.

(6) providing in conjunction with such supports suitable means, indicated generally at 17, for raising and lowering the deflector for the purpose of varying the distance between the rim 14 of the deflector and the surface of the body or film of oil within the receptacle and (0) using in lieu of the circular receptacle illustrated in Fig. 1 a receptacle of elongated form and an air aperture and deflector of corresponding shape. This burner operates in general in precisely the same manner as the burner described in connection with Fig. 1.

A burner of this type has been successfully used in practice and a temperature of approximately 1100 C. obtained within the interior of the muflle chamber 18 in less than one, half hour from the time of first igniting the surface of the body or film of oil within the receptacle. 1

The following are the particulars of the burner used Length internally of receptacle=10".

l/Vidth overall internally of receptacle=6.

Width internally across oil trough=2%.

Greatest depth internally of receptacle=2".

Length internally of air aperture; 5

Width internally of air aperture=l Height internally of side of air apcrture=1 Length internally of deflector=7% Width internally of deflector=3%".

Depth internally of deflector=1'%".

Mean distance of bottom edge of deflector above surface of body or film of oil= Air draught in the chimney= water gau e.

Oll consumption to of a gallon per hour.

By laterally altering the position of the deflector relatively to the receptacle the flame may be somewhat concentrated to one side instead of being equally distributed round the trough as when the deflector is centrally positioned.

By reason of the semi-circular cross-section of the trough the contained body or film of oil is caused at all times to tend to gravitate towards the area which is swept by the air. If a receptacle were used having a fiat bottom the tendency would be for some of the oil to reach a region of the receptacle Where it would be out of the path of the air with the result that carbonizing would occur. Such a result emphasizes the importance of causing the air to sweep over and in contact with the whole of the ignited surface of lthe body or film of oil within the receptac e.

Any suitable means may be provided for distributing the oil over the interior surface of the receptacle of a burner according to the present invention where the size of the receptacle warrants the use of such. distributing means.

A plurality of burners according to the present invention may be used in conjunction with each furnace to be fired but satisfactory results cannot be obtained with a single receptacle having more than one air deflector disposed above its surface as the resulting multiplication of air streams destroys the evenness. of flow and creates conflicting eddy currents and consequent formation of soot in the disturbed region, but a,

single deflector may be used in conjunction with a pair of receptacles.

The burner according to this invention is started by means of a piece of lighted paper or the like'deposited within the receptacle and in contact with the oil to act temporarily as a wick from which the ignition of the oil commences. Thereafter the flame spreads over the exposed surface of the oil and combustion proceeds normally.

It is not advisable to use oils containing as haltum in cases where the draught available is less than W. G. With draughts, of from to WeG. the asphaltum content of the oil should preferably not exceed 5%. With greater draughts oils containing burnt.

I claim 7 1. An oil burner comprising, in combination, a shallow trough of curved cross-sec tion, means for supplying oil to the interior of said trough so as to maintain a thin film of non-vaporized oil at the bottom of said trough, and an inlet for cold air, said inlet being formed on the inside by the inside wall of the trough and on the outside by a curved deflector which extends over and in spaced relation to the upper edge of the inside wall of the trough and downwards into the trough to a position where its bottom edge is in close proximity to the surface'of the film of oil, thus forming a narrow outlet for the cold air which is thereby caused to sweep transversely and in the form of a blanket across the whole burning surface of the oil outside the bottom edge of the deflector so as to maintain partial combustion on the surface only of the oil by removing the products of such partial combustion as fast as they are formed.'

2. An oil burner comprising, in combination, a shallow continuous trough of curved higher percentages of asphaltum may be cross-section having an inside edgeand an outside edge, the inside edge being lower than the outside edge, means for supplying oil to the interior of said trough so as to maintain a thin film of non-vaporized oil at the bottom of said trough, means for supporting said trough so as to permit cold air to enter upwards through a central aperture bounded by the inside wall of the trough, means for inducing air through said aperture at a suitable velocity, and means for causing said air to enter said trough, said means consisting of a curved deflector having a continuous lower edge and so mounted relatively to the trough that said lower edge resides within the trough and close to the surface of the contained film of oil, whereby the air is caused to issue from beneath the lower edge of the deflector in the form of a blanket and sweep transversely across the whole burning surface of the oil outside of such lower edge, thereby maintaining partial combustion on that surface of the oil which is outside of the deflector by removing the products of such partial combustion as fast as they are formed.

3. In an oil burner, the combination with an annular shallow trough of curved cross section provided with a central aperture for the entering air, of a vertically adjustable deflector comprising a circular member of close proximity to the bottom of the trough so as to leave a narrow space therebetween for the passage of am 4. An oil burner comprising, in combination, an annular trough, means for supplying oil to the interior of said trough so as to maintain a thin film of non-vaporized oil at the bottom thereof. and an inlet for cold 5 air, said inlet being formed on one side by a wall of the trough and on another side by a curved defiectonwhich extends over and in spaced relation to said wall of the trough and downwards into the trough to a position where its bottom edge is in close proximity to the surface of the film of oil, thus forming a narrow outlet for the inlet air which is thereby caused to sweep transversely and in the form of a blanket across the whole burning surface of the oil outside the bottom edge of the deflector so as to maintain partial combustion'on the surface only of the oil by removingthe products of such partial com bustion as fast as they are formed.

In testimony whereof I aflix my signature.

JOHN EDWARD HACKFORD. 

